The field of invention is the composition and application of catalysts useful for the production of insulating polyurethane foam produced with blowing agents containing a halogen.
Polyurethane foam compositions are typically prepared by reacting an isocyanate and a premix which consists of isocyanate-reactive components such as a polyol. The premix optionally also contains other components such as water, flame retardants, blowing agents, foam-stabilizing surfactants, and catalysts to promote the reactions of isocyanate with polyol to make urethane, with water to make CO2 and urea, and with excess isocyanate to make isocyanurate (trimer). The blowing agent in the premix is usually a liquid or gas with a boiling point sufficiently low to be vaporized by the heat released during the polymerization reaction. Examples of blowing agents useful in the production of insulating polyurethane foam include but are not limited to hydrofluorocarbons, hydrofluoroolefins, hydrofluorochloroolefins, hydrochlorofluorocarbons, formates, and hydrocabons. The proper selection and combination of the components in the premix and the isocyanate can be useful for the production of polyurethane foam that is spray applied, poured in place, and used in applications such as refrigerators, freezers, hot water heaters, insulation panels, garage doors, entry doors, and other various applications where insulation is desired. For some of these applications, the premix is stored for one day up to one year before being reacted with isocyanate to generate polyurethane foam. This is common in sprayfoam applications, where drums of premix and isocyanate are shipped to field locations for on-site application. Thus, it is desirable for the premix of an insulating foam formulation to be both chemically and physically stable. However, the catalysts that are useful to promote the polyurethane reaction can also participate or induce undesired reactions with the blowing agents present in the premix resulting in reduced storage stability. These undesired reactions are prevalent in blowing agents that contain halogens, and are especially problematic in halogenated blowing agents containing unsaturation and olefinic carbons. Common amine catalysts useful for the production of polyurethane foam include tertiary amines, such as N,N,N′,N″,N″-pentamethyldiethylenetriamine (available from Air Products as Polycat®-5) or 1,4-diazabicyclo[2.2.2]octane (available in solution from Air Products as Dabco®33LX) which are known to accelerate the urethane reaction promoting the formation of polyurethane polymers. However, tertiary amines are also know to react with halogen containing organic compounds causing deactivation of the tertiary amine catalysts resulting in a net decrease in the kinetic of the polymerization process. Reaction between tertiary amine and halogen containing organic compounds occurs more rapidly when the halogen atom is bound to an olefinic carbon because halogen-substituted olefins are susceptible to nucleophillic attack by tertiary amines. This results in a fast deactivation of the tertiary amine catalysts rendering the premix not active enough for reaction with the isocyanate. Deactivation of tertiary amine by reaction with halogen containing compounds can also occur in halogen containing aliphatic compounds via formation of a quaternary ammonium salt or dehydrohalogenation both pathways resulting in tertiary amine deactivation.
U.S. Pat. Appl. No. 20120313035A1, which is hereby incorporated by reference in its entirety, describes a foamable composition comprising a hydrohaloolefin blowing agent and an amine catalyst that produce a stable polyol premix. The method includes the use of 1,2-dimethylimidazole, N-methylmorpholine, and other hindered tertiary amines such as diisopropylethylamine catalysts. These catalysts suffer from the drawback that they do not contain isocyanate-reactive groups and thus are emissive from the final polyurethane foam. Additionally, it is demonstrated that reactive amine catalysts such as dimethylaminoethoxyethanol and 2-[N-(dimethylaminoethoxyethyl)]-N-methylamino ]ethanol result in an unstable polyol premix in the presence of a hydrohaloolefin.
U.S. Pat. Appl. No. 2013019415A1, which is hereby incorporated by reference in its entirety, describes a foamable composition comprising a non-emissive catalyst and a tetraalkyl guanidine catalyst. Specifically, the non-emissive catalyst can include 2-[N-(dimethylaminoethoxyethyl)]-N-methylamino]ethanol and dimethylaminoethoxyethanol, and the tetraalkyl guanidine can be tetramethylguanidine. The drawback being that the blowing agent composition is water, and will not produce a closed-cell insulating foam with the same insulation value as a foamable composition utilizing a halogenated blowing agent containing a hydrohaloolefin.
W.O. Pat. Appl. No. 2013116416A1 which is hereby incorporated by reference in its entirety, describes a foamable composition comprising an encapsulated amine catalyst and a hydrohaloolefin blowing agent. The drawback being that the amine catalyst is encapsulated in a solid thermoplastic polymer which must be dispersed in the polyol premix.
A process, a polyurethane composition, a polyurethane product, a process of producing a catalyst composition, and a catalyst that do not suffer from one or more of the above drawbacks would be desirable in the art.